The term 'Ten-Sided Solid' is a description of a three-dimensional shape known as a decahedron. A decahedron is a polyhedron with ten faces, and is one of the five Platonic solids. Platonic solids are regular, convex polyhedrons composed of congruent, regular faces with the same number of faces meeting at each vertex. The other four Platonic solids are the tetrahedron, the cube, the octahedron, and the icosahedron.